The present invention relates to fiber production and fiber treatment that renders fiber soil resistant, oil repellent, and/or water repellent.
In the formation of textile materials from extruded thermoplastic polymers, such as polypropylene, application of a spin oil to the filaments is standard practice. Spin finish including a spin oil is a lubricating composition deposited on the surface of the fiber to reduce the fiber-fiber friction and the friction developed as the yarn passes over the metal machinery surfaces. Spin oil typically contains a large number of chemical components, the major components being lubricant, antistatic agent and emulsifier. The amount of spin finish needed depends on the producer and manufacturing process, and typically the residual spin finish on the fiber varies between 0.7% and 5%. A major disadvantage of the use of a spin finish that includes a spin oil is that residues of the finish on the extruded fiber attract soil. It also decreases the efficiency of any protective treatment applied to the fiber and as such reduces the soil resistance of the finished products.
In the industrial production of textiles, such as carpet and apparel, it is common to treat such substrates with a composition to impart added desirable properties thereto, such as resistance to soiling by particulate or dry soil. Fluorochemical compositions are commercially used for this purpose. They can be applied to various substrates by methods which include, for example, spraying, foaming, padding, and finish bath immersion.
U.S. Pat. No. 4,264,484 discloses a liquid carpet treating composition containing a water-insoluble addition polymer that is derived from polymerizable ethylenically unsaturated monomer that is free of non-vinylic fluorine and has at least one major transition temperature higher than about 25xc2x0 C., and a water-insoluble fluoroaliphatic radical- and aliphatic chlorine-containing ester having at least one major transition temperature higher than about 25xc2x0 C.
U.S. Pat. No. 4,107,055 discloses a fabric coating composition, including a polymer having a glass transition temperature above room temperature, an ionic fluorinated surfactant and a carrier. The polymer is preferably applied to fabric at a rate giving a dry solids content of about 0.25 to 10%, to give dry soil resistance.
U.S. Pat. No. 4,043,964 discloses a coating which provides a durably soil-resistant carpet and which contains: (a) at least one phase of a specified, water-insoluble addition polymer derived from a polymerizable ethylenically unsaturated monomer that is free of non-vinylic fluorine, and (b) at least one phase of a specified, water-insoluble fluorinated component containing a fluoroaliphatic radical of at least 3 carbon atoms. The monomer from which the fluorinated component is formed may contain dicarboxylic acid, glycol, diamine, hydroxyamine, etc.
A common feature of the treating or coating compositions disclosed in the above-mentioned U.S. patents is that they are to be applied to the carpet or fabric after its production in a separate treating step. The application equipment and time required for such a treating step adds to the cost of the final product.
Textile fibers and yarns can also be treated by incorporation of a fluorochemical repellent treating agent in the spin finishing bath, for example, as disclosed in U.S. Pat. Nos. 4,190,545 and 4,192,754. A drawback of such a process is the formation of deposits on the rolls caused by sedimentation of the fluorochemical oil- and water-repellent agent/spin finish mixture. The deposit on the rolls can cause fiber breaks and must be removed frequently. This is time consuming and expensive and is no longer accepted as an application method by fiber manufacturers. Typically, the more spin finish added to the fluorochemical treating agent, the more roll build up occurs, and the greater the reduction in repellent properties of the finished product because of the high level of spin oil present on the treated substrate.
Alternatively, treated textile fibers and yarns can be obtained by melt extrusion of a blend of a synthetic fiber-forming polymer and a fluorochemical composition. Such melt extrusion is described for example in U.S. Pat. No. 3,839,312. This patent discloses that soil and stain repellency of extruded filaments of a synthetic resin can be improved by incorporating in the resin a small amount, about 1 percent, of an amphipathic compound having from one to four fluoroalkyl groups pendent from an organic radical. The repellency is provided by the fluoroalkyl groups, which tend to be concentrated at the surface of the fiber.
WO 92/18569 and WO 95/01396 disclose permanently soil resistant polymeric compositions such as fibers and yarns that have a fluorochemical dispersed throughout the polymer. These polymer compositions are prepared by melt extrusion of the fluorochemical with the desired polymer. Polymers that can be used with the fluorochemical include polyester, polypropylene, polyethylene and polyamide.
U.S. Pat. No. 5,025,052 discloses certain fluoroaliphatic group-containing oxazolidinone compositions. The patent also discloses fibers, films, and molded articles prepared, for example, by injection molding a blend or mixture of fiber-or film-forming synthetic organic polymers and certain fluorochemical oxazolidinones. The resulting fibers, films, and molded articles are said to have low surface energy, oil and water repellency, and anti-soiling properties.
European Pat. Pub. No. 0 516 271 discloses durably hydrophilic thermoplastic fibers comprising thermoplastic polymer and fluoroaliphatic group-containing non-ionic compounds.
While the above-mentioned publications, U.S. Pat. No. 3,839,312, WO 92/18569 and WO 95/01396, are successful in providing soil and stain repellency to a yarn or fiber and many currently used fluorochemical compositions have demonstrated utility in providing carpet with soil resistance, unfortunately a significant amount of the carpet or fabric manufactured cannot be treated to obtain the desired properties. The reason is that significant and varying amounts of spin oil often remain on the fiber or yarn, lowering the soiling resistance thereof or acting as contaminants which interfere with the fluorochemical treatment and diminish or prevent the desired result thereof.
WO 97/33019 discloses a carpet yarn that contains a hydrophilicity imparting compound dispersed in the filaments of thermoplastic polymer. Fluorochemical hydrophilicity imparting compounds are disclosed as preferred hydrophilicity imparting compounds. It is taught that as a result of the use of the hydrophilicity imparting compound in the filaments of the yarn, less or no spin oil is needed in the spin finishing bath and as a result, the carpet is less prone to soiling. Although this method is successful, the oil and/or water repellency properties of the obtained fibers is generally poor and there continues to be a desire to improve the soil repellency properties.
In one aspect, the invention provides a process for obtaining a fiber comprising the steps of:
melt extruding a mixture of thermoplastic polymer and hydrophilicity imparting compound to form a plurality of filaments;
applying a spin finish to said filaments;
and spinning said filaments into a fiber;
wherein said spin finish comprises fluorochemical. In preferred embodiments, the fluorochemical is an effective oil and/or water repellent and it imparts good oil and water repellency properties to the fiber.
One advantage of the invention is that roll build-up does not occur on the fibers made according to the process even though the application of spin finishes comprising fluorochemical to thermoplastic fibers typically results in roll build-up. Also, the resulting fibers generally show good oil and water repellency properties and soil resistance. Additionally, low levels of spin oil can be employed on fibers made according to the invention without sacrificing their antistatic properties.
In another aspect, the invention provides a fiber containing a plurality of filaments of a thermoplastic polymer having dispersed therein hydrophilicity imparting compound characterized in that the filaments comprise on at least part of their surface fluorochemical. As previously noted, the fluorochemical preferably is an effective oil and/or water repellent treatment and it imparts good oil and water repellency properties to the fiber. In yet another aspect, the invention provides a carpet or textile comprising such fibers.
Thermoplastic polymers useful in the invention include fiber-forming poly(alpha)olefins, polyesters and polyamides. Preferred thermoplastic polymers are poly (alpha)olefins. Poly(alpha)olefins useful in the invention can include the normally solid, homo-, co- and terpolymers of aliphatic mono-1-olefins (alpha olefins) as they are generally recognized in the art. Usually, the monomers employed in making such poly(alpha)olefins contain 2 to about 10 carbon atoms per molecule, although higher molecular weight monomers sometimes are used as comonomers. Blends of the polymers and copolymers prepared mechanically or in situ may also be used. Examples of monomers that can be employed in the invention include ethylene, propylene, butene-1, pentene-1, 4-methyl-pentene-1, hexene-1, and octene-1, alone, or in admixture, or in sequential polymerization systems.
Examples of preferred thermoplastic poly(alpha)olefin polymers include polyethylene, polypropylene, propylene/ethylene copolymers, polybutylene and blends thereof Polypropylene is particularly preferred for use in the invention.
Processes for preparing the thermoplastic polymers useful in this invention are well known, and the invention is not limited to a polymer made with a particular catalyst or process.
Hydrophilicity imparting compounds useful in this invention may be fluoro-chemical or non-fluorochemical, mixtures of such compounds or mixtures of fluorochemical compounds and non-fluorochemical compounds. Non-fluorochemical hydrophilicity imparting compounds are substantially free of fluorine (preferably containing less than about 10% by weight and more preferably less than about 5% by weight of fluorine) and are generally hydrophilic in nature or contain at least a sufficient number of hydrophilic moieties such that hydrophilicity or wettability is provided to the surface of the thermoplastic polymer filaments. Included are low molecular weight compounds, oligomers and polymers. Suitable non-fluorochemical hydrophilicity imparting compounds are preferably incompatible with the thermoplastic polymer melt and are preferably stable at the required extrusion temperatures.
Suitable non-fluorochemical hydrophilicity imparting compounds can be anionic, cationic, non-ionic or amphoteric. Preferred compounds include compounds which are known to have utility as surfactants. Particularly preferred non-fluorochemical hydrophilicity imparting compounds are those that contain at least one poly(oxyalkylene) group.
Fluorochemical hydrophilicity imparting compounds useful in the invention are hydrophilic in nature and can include compounds, oligomers, and polymers. Such materials will contain at least about 10% by weight of fluorine (i.e., carbon-bonded fluorine). They contain one or more fluorochemical radicals (Rf), and one or more water solubilizing polar groups (Z), which radicals and groups are usually connected together by suitable linking groups (Q).
The fluorochemical radical, Rf, in the fluorochemical hydrophilicity imparting compound can be generally described as a fluorinated, preferably saturated, monovalent radical of at least about 4 carbon atoms. Preferably the fluorochemical radical is a fluoroaliphatic, non-aromatic radical. The aliphatic chain may be straight, branched, or, if sufficiently large, cyclic, and it may include oxygen, di- or hexavalent sulfur, or trivalent nitrogen atoms bonded only to carbon atoms. A fully fluorinated radical is preferred, but hydrogen or chlorine atoms may be present as substituents provided that no more than one atom of either is present for every two carbon atoms. Fluoroaliphatic radicals containing about 5 to about 12 carbon atoms are most preferred.
The water solubilizing polar group or moiety, Z, of fluorochemical hydrophilicity imparting compound can be a non-ionic, anionic, cationic, or amphoteric moiety, or combinations of said groups or moieties which may be the same or different. Preferably, the water solubilizing group comprises a poly(oxyalkylene) group, (ORxe2x80x2)x, where Rxe2x80x2 is an alkylene group having 2 to about 4 carbon atoms, such as xe2x80x94CH2CH2xe2x80x94, xe2x80x94CH2CH2CH2xe2x80x94, xe2x80x94CH(CH3)CH2xe2x80x94, and xe2x80x94CH(CH3)CH(CH3)xe2x80x94 or mixtures thereof, and x is an integer from about 6 to about 20. The oxyalkylene units in said poly(oxyalkylene) may be the same, as in poly(oxypropylene), or present as a mixture, such as in a heteric, straight or branched chain of randomly distributed oxyethylene and oxypropylene units (e.g., poly(oxyethylene-co-oxypropylene), or as in a straight or branched chain of blocks of oxyethylene units and blocks of oxypropylene units. The poly(oxyalkylene) chain can be interrupted by or include one or more catenary linkages, providing such linkages do not substantially alter the water-solubilizing character of the poly(oxyalkylene) chain. The Z group is terminated with hydroxyl or lower alkyl ether for example, xe2x80x94OCH3 or xe2x80x94OCH2CH3. Typical anionic groups include CO2H, CO2M, SO3H, SO3M, OSO3H, OSO3M, OPO(OH)2, and OPO(OM)2, where M is a metallic ion (such as sodium or potassium), or ammonium ion, or other amine cation. Typical cationic groups include NR3+Axe2x88x92, where R is a lower alkyl group such as methyl, ethyl, butyl, hydroxyethyl or hydrogen and A is an anion such as chloride, sulfate, phosphate, hydroxide or iodide. Typical mixed or amphoteric groups would include N+(CH3)2C2H4COOxe2x88x92, N+(CH3)2C3H6SO3xe2x88x92 or an amine-oxide.
The linking group, Q, is a multivalent, generally divalent, linking group such as alkylene, arylene, sulfonamidoalkylene, carbonamidoalkylene, and other heteroatom-containing groups such as siloxane, including combinations of such groups. In some instances, more than one fluoroaliphatic radical may be attached to a single linking group. In other instances, a single fluoroaliphatic radical may be linked by a single linking group to more than one polar solubilizing group. Q can also be a covalent bond.
A particularly useful class of fluorochemical hydrophilicity imparting compounds are represented by the formula
Rfxe2x80x94Qxe2x80x94Z
where Rf is said fluoroaliphatic radical, Q is said linking group and Z is said water solubilizing group.
Hydrophilicity imparting fluorochemical non-ionic compounds useful in the present invention can be prepared using known methods such as those described in U.S. Pat. No. 2,915,554 (Albrecht et al.). The Albrecht patent discloses the preparation of fluoroaliphatic group-containing, non-ionic compounds from active hydrogen containing fluorochemical intermediates, such as fluoroaliphatic alcohols, e.g. RfC2H4OH, acids e.g., RfSO2N(Rxe2x80x3)CH2COOH, and sulfonamides, e.g., RfSO2N(Rxe2x80x3)H, by reaction of the intermediates with, for example, ethylene oxide to yield, respectively, RfC2H4O(C2H4O)nH, RfSO2N(Rxe2x80x3)CH2CO2(C2H4O)nH, and RfSO2N(Rxe2x80x3)(C2H4O)nH, where n is a number greater than about 3, and Rxe2x80x3 is hydrogen or lower alkyl (e.g., 1 to about 6 carbons). Analogous compounds can be prepared by treating the intermediates with propylene oxide or a mixture of ethylene oxide and propylene oxide. See also the fluoroaliphatic oligomers disclosed in U.S. Pat. No. 3,787,351 (Olson), and certain fluorinated alcohol-ethylene oxide condensates described in U.S. Pat. No. 2,723,999 (Cowen et al.).
The hydrophilicity imparting compound is typically added in amounts between about 0.05 and about 5% by weight, preferably between about 0.5 and about 1.5% by weight, based on the total weight of thermoplastic polymer.
Some examples of hydrophilicity imparting compounds include:
C8F17SO2N(C2H5)CH2CH2O(CH2CH2O)7CH3 
2 C8F17SO3H
Jeffamine(trademark) ED-600 di-salt (Jeffamine(trademark) ED 600 is an amino terminated ethylene oxide-propylene oxide polymer)
copolymers of fluorochemical acrylates or methacrylates
mono-acrylate or mono-methacrylates of polyethyleneoxide
C8H17SO2N(C2H5)(CH2CH2O)2xe2x80x94(CH(CH3)CH2O)6H
polyethylene oxide
copolymers of ethylene oxide and propylene oxide
ethoxylated alkyl phenols (such as Triton(trademark) X-100, available from Union Carbide, Danbury, Conn.)
A fiber or yarn can be produced in accordance with the invention by providing a mixture comprising thermoplastic polymer and one or more hydrophilicity imparting compounds. This mixture can be extruded to form filaments which are then preferably cooled. The bundle of filaments is then typically treated in a spin finish bath. After receiving the spin finish treatment, the filaments are generally stretched. Stretching may be accomplished over a number of rolls that are at elevated temperature sufficient to soften the thermoplastic polymer. By rotating the rolls at different speeds, stretching of the filaments can be obtained. While stretching can be accomplished in one step, it may be desirable to stretch the filaments in two steps. Typically, the filaments will be stretched 3 to 4 times the extruded length. Subsequent to stretching, and in order to obtain a carpet yarn, it will often be desirable to texture the yarn with pressured air at an elevated temperature or steam jet and to subject it to an entanglement.
In accordance with the present invention, the spin finish comprises fluorochemical. Preferably, such fluorochemical is an effective oil and/or water repellent. Typically, the amount of fluorochemical in the spin finish will be between about 0.1% by weight and about 5% by weight, preferably between about 0.5% by weight and about 3% by weight. In general, the fluorochemicals useful in the invention include any of the known fluoroaliphatic radical-containing agents useful for the treatment of fabrics to obtain oil and water repellency. Fluorochemical radical-containing agents such as condensation polymers like polyesters, polyamides or polyepoxides, and vinyl polymers like polyacrylates, polymethacrylates or polyvinyl ethers are generally effective choices. Such known agents include, for example, those described in U.S. Pat. Nos. 3,546,187, 3,544,537, 3,470,124, 3,445,491, 3,341,497 and 3,420,697.
Further examples of useful fluoroaliphatic radical-containing water and oil repellency imparting agents include those formed by the reaction of perfluoroaliphatic glycols or thioglycols with diisocyanates to provide perfluoroaliphatic group-containing polyurethanes. These products are normally applied to fibers as aqueous dispersions. Such reaction products are described, for example, in U.S. Pat. No. 4,054,592. Another group of useful fluorochemicals are fluoroaliphatic radical-containing, N-methylol condensation products. These compounds are described in U.S. Pat. No. 4,477,498. Other examples of useful fluorochemicals include fluoroaliphatic radical containing polycarbodiimides which can be obtained, for example, by reaction of perfluoroaliphatic sulfonamido alkanols with polyisocyanates in the presence of suitable catalysts.
The fluorochemical can be a copolymer of one or more fluoroaliphatic radical-containing acrylate or methacrylate monomers, and one or more fluorine-free (or hydrocarbon) terminally ethylenically-unsaturated comonomers. Representative examples of such fluorochemical monomers include:
CF3(CF2)4CH2OC(O)C(CH3)xe2x95x90CH2 
CF3(CF2)6(CH2)2OC(O)C(CH3)xe2x95x90CH2 
CF3(CF2)6(CH2)2OC(O)CHxe2x95x90CH2 
CF3(CF2)7(CH2)2OC(O)CHxe2x95x90CH2
The preferred monomers to copolymerize with the above-described fluoroaliphatic radical-containing monomers include those selected from the group consisting of octadecylmethacryate, 1,4-butanediol diacrylate, laurylmethacrylate, butylacrylate, N-methylol acrylamide, isobutylmethacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, vinylchloride and vinylidene chloride. The relative weight ratio of the fluoroaliphatic monomer(s) to the hydrocarbon co-monomer(s) can vary and is taught in the art.
Further examples of useful fluorochemicals include, for example, fluorinated group containing urethanes, ureas, esters, amines (and salts thereof), amides, acids (and salts thereof), carbodiimides, guanidines, allophanates, biurets, oxazolidinones, and other substances containing one or more fluorinated groups, as well as mixtures and blends thereof. Such agents are well known to those skilled in the art, see e.g., Kirk-Othmer, Encyclopedia of Chemical Technology, 3rd Ed., Vol. 24, pp. 448-451 and many (e.g., SCOTCHGARD(copyright) Fabric Protector, 3M) are commercially available as ready-made formulations.
In addition to the fluorochemical, the spin finish typically also includes any conventional spin oil used on extruded thermoplastic polymers. However, the spin finish may be aqueous without any spin oil. The spin finish can be applied using methods known in the art. One example includes kiss roll application. The lower part of the kiss roll dips in the finish bath, while the yarn tangentially moves over the top part. The add-on level of spin oil can be varied by changing several parameters, such as the geometry between yarn and roll, roll speed and the concentration of spin oil in the spin finishing bath. When spin oil is used, the parameters will be adjusted so that the residual amount of spin oil on the filament will be between about 0.01% and about 1.2% by weight, preferably between about 0.01% and about 0.6% by weight, based on the total weight of filaments and spin oil. Most preferably, the residual amount of spin oil will be less than about 0.4%.
The following examples further illustrate the invention without however the intention to limit the invention thereto.